Perceptual and Motor Skilk, 1990, 70, 57-58. O Perceptual and Motor Skills 1990
GEOPHYSICAL VARIABLES A N D BEHAVIOR: LIX. THE SEASONAL VARIATION IN SUICIDE RATES: T H R E E STUDIES ' DAVID LESTER AND MICHAEL L. FRANK Richard Stockton S ~ t College e Summary.-The seasonal variation in suicide in the USA was not more pronounced in 1980 in northern regions but was more clear for married people than for those with other marital statuses. The seasonal variation in suicide was not associated with the gross domestic product of the region.
(I) Lester and Frank (1988) showed that the monthly variation in suicide rates in the USA produced a Spring and a Fall peak. A climatic explanation of this seasonal variation suggests that the seasonal variation of suicide should be found only in those regions with a strong climatic variation in weather. Thus, the seasonal variation of suicide should be stronger in the northern regions. To explore this, the monthly distributions of suicides in the nine major regions of the USA were compared with chance expectations using data from 1980 (National Center for Health Statistics, 1983). The monthly distribution of suicides differed from chance expectations only for the Middle Atlantic, South Atlantic, and East South Central regions = 22.45, 21.38, and 20.09). The monthly distribution of suicides did not differ from chance expectations for the New England, North East Central, North West Central, West South Central, Mountain or Pacific regions. (Over the total USA, the seasonal distribution of suicides was also significantly different from chance [X,12 = 28.721. For each state, only the distributions in Ihnois, Nebraska, and New York differed significantly from chance.) For the USA as a whole, the distribution was bimodal, with a major peak in April and a minor peak in August. The Middle Atlantic region had a major peak in May and a minor peak in December. The South Atlantic region had a major peak in September and a minor peak in AprilIJune. The East South Central region had a major peak in April and a minor peak in August. Although the different regions of the USA had different monthly distributions of suicide, there was no clear pattern that showed more of a seasonal trend in the northern regions and less in the southern regions. Furthermore, the precise pattern identified for the USA as a whole was found only in the East South Central region. 'Address correspondence to M. L. Frank, Ph.D., Psychology Program, Richard Stockton State Yollege, Pomona, NJ 08240-9988. In contrast, seven of the nine regions had a monthly distribution of homicides that differed significantly from chance. Six had the peak in August while three had the peak in July.
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(2) It has long been known that suicide rates are higher in the Spring than at other seasons (Dublin, 1963). A social psychological explanation of this phenomenon has focused on changes in patterns of social interaction in the Spring, in which those who are socially isolated come to experience their loneliness more than at other seasons (Lester, 1972). If this is the case, then the seasonal variation in suicide might be expected to be less pronounced in those who are married than in those who are not. To explore t h s , the monthly distribution of suicidal deaths in the USA in 1980 for each marital status was compared to chance expectations using data from the National Center for Health Statistics (1985). The distribution of suicides by month for the married individuals differed from chance ( X , , 2 = 23.52) with a peak in April. The distributions for those never married, widowed, and divorced did not differ from chance and did not peak in April.' This study, then, failed to confirm the prediction and, in fact, indicated that only married people in the USA in 1980 showed the Spring peak in suicides. (3) Abe, et al. (1986) reported that the degree of seasonal variation in suicide and the gross national product per capita were negatively related in Japan over the period 1900-1982. The present study examined this association over the continental states of America in 1980. The seasonal variation in suicide for each state was calculated by computing chi-squared for the monthly suicide totals in each state and converting this to a contingency coefficient to control for the number of suicides. The gross state product per capita for each state was obtained from Renshaw, et al. (1988). The Pearson correlation between the two variables was 0.02 which is not statistically significant, so the result of Abe, et al. does not appear to generalize to the regional variation in the seasonality of suicide over the continental states of America. REFERENCES K., & S u m , T. Suicide seasonality and economic growth. Stress Med., ABE, K., EGASHIRA, 1986, 2, 79-81. DUBLIN, L. I . Suicide. New York: Ronald, 1963. LESTER,D. Why people kill themselves. Springfield, IL: Thomas, 1972. LESTER,D., & FUNK, M. L. Sex differences i n the seasonal distribution of suicides. Brit. J. Psvchiat.. 1988.. 153.. 115-117. N A ~ O NCENTER N FOR HENTH STATISTICS.Data tape update: No. 8. Hyattsville, MD: Author, 1985. RENSHAW, V., TROT, E. A., & FEDENBERG,H. L. Gross state product by industry, 1963-86. Szrrvey of Current Business, 1988, May, 30-46. January 6, 1990
'In contrast, the monthly distribution of homicides did differ from chance for those never married, married, and divorced, and the peak for all four groups was in August.
GEOPHYSICAL VARIABLES A N D BEHAVIOR: LIX. THE SEASONAL VARIATION IN SUICIDE RATES: T H R E E STUDIES ' DAVID LESTER AND MICHAEL L. FRANK Richard Stockton S ~ t College e Summary.-The seasonal variation in suicide in the USA was not more pronounced in 1980 in northern regions but was more clear for married people than for those with other marital statuses. The seasonal variation in suicide was not associated with the gross domestic product of the region.
(I) Lester and Frank (1988) showed that the monthly variation in suicide rates in the USA produced a Spring and a Fall peak. A climatic explanation of this seasonal variation suggests that the seasonal variation of suicide should be found only in those regions with a strong climatic variation in weather. Thus, the seasonal variation of suicide should be stronger in the northern regions. To explore this, the monthly distributions of suicides in the nine major regions of the USA were compared with chance expectations using data from 1980 (National Center for Health Statistics, 1983). The monthly distribution of suicides differed from chance expectations only for the Middle Atlantic, South Atlantic, and East South Central regions = 22.45, 21.38, and 20.09). The monthly distribution of suicides did not differ from chance expectations for the New England, North East Central, North West Central, West South Central, Mountain or Pacific regions. (Over the total USA, the seasonal distribution of suicides was also significantly different from chance [X,12 = 28.721. For each state, only the distributions in Ihnois, Nebraska, and New York differed significantly from chance.) For the USA as a whole, the distribution was bimodal, with a major peak in April and a minor peak in August. The Middle Atlantic region had a major peak in May and a minor peak in December. The South Atlantic region had a major peak in September and a minor peak in AprilIJune. The East South Central region had a major peak in April and a minor peak in August. Although the different regions of the USA had different monthly distributions of suicide, there was no clear pattern that showed more of a seasonal trend in the northern regions and less in the southern regions. Furthermore, the precise pattern identified for the USA as a whole was found only in the East South Central region. 'Address correspondence to M. L. Frank, Ph.D., Psychology Program, Richard Stockton State Yollege, Pomona, NJ 08240-9988. In contrast, seven of the nine regions had a monthly distribution of homicides that differed significantly from chance. Six had the peak in August while three had the peak in July.
58
D. LESTER & M. L. FRANK
(2) It has long been known that suicide rates are higher in the Spring than at other seasons (Dublin, 1963). A social psychological explanation of this phenomenon has focused on changes in patterns of social interaction in the Spring, in which those who are socially isolated come to experience their loneliness more than at other seasons (Lester, 1972). If this is the case, then the seasonal variation in suicide might be expected to be less pronounced in those who are married than in those who are not. To explore t h s , the monthly distribution of suicidal deaths in the USA in 1980 for each marital status was compared to chance expectations using data from the National Center for Health Statistics (1985). The distribution of suicides by month for the married individuals differed from chance ( X , , 2 = 23.52) with a peak in April. The distributions for those never married, widowed, and divorced did not differ from chance and did not peak in April.' This study, then, failed to confirm the prediction and, in fact, indicated that only married people in the USA in 1980 showed the Spring peak in suicides. (3) Abe, et al. (1986) reported that the degree of seasonal variation in suicide and the gross national product per capita were negatively related in Japan over the period 1900-1982. The present study examined this association over the continental states of America in 1980. The seasonal variation in suicide for each state was calculated by computing chi-squared for the monthly suicide totals in each state and converting this to a contingency coefficient to control for the number of suicides. The gross state product per capita for each state was obtained from Renshaw, et al. (1988). The Pearson correlation between the two variables was 0.02 which is not statistically significant, so the result of Abe, et al. does not appear to generalize to the regional variation in the seasonality of suicide over the continental states of America. REFERENCES K., & S u m , T. Suicide seasonality and economic growth. Stress Med., ABE, K., EGASHIRA, 1986, 2, 79-81. DUBLIN, L. I . Suicide. New York: Ronald, 1963. LESTER,D. Why people kill themselves. Springfield, IL: Thomas, 1972. LESTER,D., & FUNK, M. L. Sex differences i n the seasonal distribution of suicides. Brit. J. Psvchiat.. 1988.. 153.. 115-117. N A ~ O NCENTER N FOR HENTH STATISTICS.Data tape update: No. 8. Hyattsville, MD: Author, 1985. RENSHAW, V., TROT, E. A., & FEDENBERG,H. L. Gross state product by industry, 1963-86. Szrrvey of Current Business, 1988, May, 30-46. January 6, 1990
'In contrast, the monthly distribution of homicides did differ from chance for those never married, married, and divorced, and the peak for all four groups was in August.
